I was getting frustrated with the intermittent stalling that was being suffered by my pair of older Kato F units. These are the variety with the solid frame, and the trucks that pick up through wipers that rub directly on the frame.
At first I would notice them stalling on the usual suspects: unpowered turnout frogs... but then I noticed they would stall at other locations around the layout as well, mostly in the temporary section that I added hastily, which has a few uneven sections. None of my newer engines have a problem through here, but this A-B set would drive me mad.
The problem is that the pickups in the trucks are ridged, and any unevenness in the track causes one or the other wiper to lose contact with the frame. Kato Perfect Track Syndrome, I've come to call it. Well, my track is not perfect, but I don't have this problem with any other engine, so I'm not going to call the track the problem.
So, to the Bat Cave, soldering pencil in hand!
I disassembled one truck, and burnished the little ear at the top of the wiper, then tinned it with a tiny amount of solder.
Then, I took one of those little phosphor bronze springs that back up a Rapido Coupler. (I've got a million of these floating around... I knew I'd find a purpose for them sooner or later!) I tin one end of that, then attach it to the ear of the wiper, creating a springy brush that can now flex and maintain constant contact with the frame.
Now, I have two of these, and one is the original design with the die cast metal truck frame, so there's nowhere to solder a wiper. Since these older trucks are interchangeable with the newer tabbed ones, I simply took the rear truck from the A unit, and swapped it for the lead truck on the B, so now each engine has one old and one new truck, with no discernible impact on operation.
I have the brushes installed to point toward the end of the engine. This does two things: 1- the added springiness pushes the front wheel of the truck down a bit, and having that be the lead wheelset helps it track better, and 2 - it keeps the brushes away from the spinning flywheel over the inboard end of the truck.
So give that a whirl, and see how it works for you...
Lee
